sayow

Have a friend who bought a near mint 94 LS that had just under 90k original miles with a bad motor. He swapped in a 90 or 91 motor and now says the car runs like crap, no power and all dash lights are out.

I instantly think ECU save for the fact he says he smells gas when it idles.

So I ask the experts:

1. Does this sound like an ECU issue?
2. Could the fuel smell be related?
3. A 94 with a 90 or 91 motor should use which ECU? 94 that's in it or get an ECU to match motor year?

Thanks!

LScowboyLS

a faulty ECU can cause a gas smell, but there could be all kinds of other reasons for the running like crap and gassy smell besides the ECU

he should run Yamae's ripple test!

sayow

I will pass that on, but could someone confirm that a 94 LS with a 94 ECU will operate fine if the motor is changed out to a 90 or 91?

What is proper? Should he be installing a 90 or 91 ECU?

LScowboyLS

the year of the ECU should match the year of the car, as should the harness, and the major sensors in the car such as the AFM/MAF, and ECTS, etc. if any part numbers are different - if I was swapping engines, I would just swap as little as possible.

PureDrifter

iTrader: (10)

if you swapped just the motor and used ALL the electrical bits from whatever negine was in the car, you can get away with it.

if you mixed/matched bits from both cars, you're in for a fun time.

Yamae

There was a big design change in August 1992. There are many different changes. One of the items is that the new engine has O2 sensors with the built in heater. The ECU was added the function to control the DC power to heaters as well as the new algorithm to control the emission / combustion. It is natural that your engine may be started but does not run properly.